The deoxyglucose method is being used to study alterations in local cerebral glucose utilization in rats during the performance of goal-oriented self-stimulation behavior. By mapping metabolic activity in rats during electrical stimulation to various discrete areas of the brain, information can be obtained about those areas of the brain involved in motivation, learning, and reinforcement of behavior. Also studying the effects of drugs of abuse such as the psychostimulants and opiates with the deoxyglucose method will provide information about the areas in the brain which mediate the reinforcing properties of these drugs.